This is a fourth revision of a proposal to conduct a two year study of the driving competence and risks for negative driving outcomes (i.e., traffic accidents and violations) in adolescents and young adults with Attention Deficit Hyperactivity Disorder (ADHD) relative to a clinical control group and a normal control group of adolescents. In the U.S., traffic accidents account for nearly half of all adolescent deaths and nearly two thirds of deaths between ages 15 and 24. Teenage drivers account for a significant number of traffic fatalities, accidents, and injuries. Our pilot studies indicate that adolescents and young adults with ADHD may have a three fold greater risk of auto accidents and a four fold risk for traffic violations than their normal peers. The extent of this elevated risk and the reasons for it have not been well studied. We propose to conduct a thorough study of the driving competence, abilities, and negative driving outcomes of a large sample of 17-19 year old ADHD subjects (N=80) and contrast these findings with those for two control groups (N-80 each). One control group will consist of a group of teens and young adults who had previously been identified as learning disabled (LD) but who are not ADHD. The other will be subjects with no history of LD or ADHD. All subjects will be evaluated on a multi-method multi-source battery of driving measures. These measures include laboratory tests of mental functions related to driving ability, simulated driving tests, parent ratings of adolescent driving ability and negative outcomes, as well as government and insurance company records of accidents, damages, and injuries. The relationship which co- morbid oppositional and conduct disorder symptoms as well as substance use and abuse may have to decreased driving competence and increased negative outcomes will also be assessed. The results should reveal the nature and extent of problems in driving competence and risks specific to both ADHD and LD teens and young adults. They should also suggest avenues for future intervention studies to alter such incompetencies and risks as well as clarify what legal liabilities are posed to practitioners who evaluate and treat ADHD adolescents wishing to drive. The findings may also reveal which measures would be most useful in a battery assessing driving competence in other psychiatric and disabled populations.